I need show the following is an identity. (thanks)
cos(3t)=4cos^3(t)-3cos(t)
Hey TrimHonduras.
Hint: Try using the sum of angles of formula to get cos(3t) down to cos(2t), cos(t), sin(2t) and sin(t) and then use it again to get sin(2t) in terms of sin(t) and cos(t) and also cos(2t) in terms of sin(t) and cos(t) and then collect everything together.